1. Field of the Invention
The present invention relates to a semiconductor device in which an interlayer insulating film having a low dielectric constant is formed by coating a copper wiring, and to a method of manufacturing the same.
2. Description of the Prior Art
In recent years, with the progress of the higher integration of semiconductor integrated circuit devices, higher speed of the data transfer rate is demanded. For this reason, an insulating film having a low dielectric constant to give only a small RC delay (referred to as a xe2x80x9clow dielectric constant insulating filmxe2x80x9d hereinafter) is employed. Examples of such xe2x80x9clow dielectric constant insulating filmsxe2x80x9d are SiOF films having a relative dielectric constant of 3.5 to 3.8, and porous SiO2 films having a relative dielectric constant of 3.0 to 3.1, etc.
In addition, a low dielectric constant interlayer insulating film having a relative dielectric constant on the order of 2 is needed. In order to form such a low dielectric constant interlayer insulating film, the plasma enhanced CVD method employing trimethylsilane (SiH(CH3)3) and N2O has been employed. For example, this plasma enhanced CVD method is set forth in M. J. Loboda, J. A. Seifferly, R. F. Schneider, and C. M. Grove: Electrochem. Soc. Fall Meeting Abstracts, p.344 (1998), etc. Also, the plasma enhanced CVD method employing tetramethylsilane (SiH(CH3)4) and N2O is set forth in J. Shi, M. A-Plano, T. Mountsier, and S. Nag; SEMICON Korea Technical Symposium 2000, p.279 (2000), etc.
In addition, a plasma enhanced CVD method employing phenylsilane, etc. has also been known. For example, such method is set forth in K. Endo, K. Shinoda, T. Tatsumi, 46-th Japanese Applied Physics Society Spring Meeting (1999), p.897, N. Matsushita, Y. Morisada, Y. Naito, S. Matsuno, 60-th Japanese Applied Physics Society Fall Meeting (1999), 1p-ZN-9(1999), Y. Uchida, T. Matsuzawa, S. Kanno, M. Matsumura, 4-th Japanese Applied Physics Society Spring Meeting, p.897 (1999), etc.
However, since the low dielectric constant interlayer insulating film formed by the plasma enhanced CVD method employing trimethylsilane (SiH(CH3)3) and N2O contains a large quantity of carbon (C), there is the problem that working by etching, etc., is difficult.
Also, in the low dielectric constant interlayer insulating film formed by the plasma enhanced CVD method employing the film-forming gas in the prior art, there is the problem that the relative dielectric constant varies widely with the film-forming conditions such as the plasmanizing power, the film-forming temperature, etc., and thus it is difficult to reliably get a relative dielectric constant on the order of 2.7.
It is an object of the present invention to provide a method of forming a low dielectric constant insulating film that can be easily worked by etching, etc., and has a relative dielectric constant on the order of 2.7, and a semiconductor device including such a low dielectric constant insulating film.
In the present invention, an interlayer insulating film having a low dielectric constant is formed by reaction of a plasma of a film-forming gas containing, as an oxygen-containing gas, N2O, H2O, or CO2, ammonia (NH3), and at least one of an alkyl compound having a siloxane bond and methylsilane (SiHn(CH3)4xe2x88x92n: n=0, 1, 2, 3).
By addition of ammonia (NH3) to a mixed gas of the alkyl compound having the siloxane bond and an oxygen-containing gas selected from N2O, H2O, and CO2, the amount of oxygen (O) can be finely controlled, and thus the insulating film will have an appropriate amount of carbon (C) and a relative dielectric constant on the order of 2.7.
Likewise, if ammonia (NH3) is added to a mixed gas of methylsilane (SiHn(CH3)4xe2x88x92n: n=0, 1, 2, 3) and an oxygen-containing gas selected from N2O, H2O, and CO2, an insulating film having an appropriate amount of carbon (C) and a relative dielectric constant of on the order of 2.7 can be reliably formed.
Likewise, if ammonia (NH3) is added to a mixed gas of the alkyl compound having the siloxane bond, the methylsilane (SiHn(CH3)4xe2x88x92n: n=0, 1, 2, 3) and an oxygen-containing gas selected from N2O, H2O, and CO2, an insulating film in which an amount of carbon (C) is appropriate and the relative dielectric constant is on the order of 2.7 can be reliably formed.
As described above, according to the present invention, since the film is formed by the plasma enhanced CVD method employing a film-forming gas to which ammonia (NH3) is added, an insulating film containing an appropriate amount of carbon (C) and having a relative dielectric constant on the order of 2.7 can be thereby formed.